Inhibition of polyamine synthesis blocks urinary secretion of beta-glucuronidase from mouse kidney

The effect of inhibition of polyamine synthesis on castrated male mouse kidney beta-glucuronidase induction and secretion by testosterone was studied. Inhibition of the activities of polyamine synthesis key-enzymes, L-ornithine and S-adenosyl-L-methionine decarboxylases, was performed with the combined treatment of 2-difluoromethylornithine and methylglyoxal' bis(guanylhydrazone). Blockage of polyamine synthesis did not affect testosterone-induced increase in renal beta-glucuronidase but blocked its secretion into the urine. After withdrawal of inhibitor-treatment beta-glucuronidase secretion normalized, and repeated testosterone administration produced undisturbed beta-glucuronidase secretion peak in urine suggesting that blockage of beta-glucuronidase secretion was not due to the tissue damage produced by inhibitors. These results indicate that the stimulation of renal polyamine synthesis by testosterone is not necessary for the induction of beta-glucuronidase but is required for the urinary secretion of this protein.     

Calcification of the Intervertebral Discs and Curvature of the Radius and Ulna: A Radiographic Survey of Finnish Miniature Dachshunds

The vertebral column of 124 randomly selected miniature dachshunds, representing 4.5% of the population registered by the Finnish Kennel Club during the years 1988 to 1996, were radiographed. The front legs were also radiographed in order to evaluate the curvature of the radius and ulna. Calcified discs were found in 75.9% of the longhaired miniature dachshunds and in 86.7% of the wirehaired ones. The occurrence of signs associated with IDD was 16.5% in longhaired and 15.6% in wirehaired miniature dachshunds. The occurrence of signs of IDD in dogs with calcified discs was 20.0% and 17.9% in long-haired and wirehaired miniature dachshunds, respectively. In dogs without calcifications only one dog showed signs of IDD. The curvature of the radius and the ulna did not differ between the dogs with signs of IDD and the healthy ones, or between the dogs with and without intervertebral calcifications. Our results indicate that radiographic eradication based on the presence of intervertebral calcifications is not suitable for breeding purposes for the Finnish miniature dachshund population because the percentage of dogs without calcifications is small.     

30-kDa heparin-binding protein of brain (amphoterin) involved in neurite outgrowth. Amino acid sequence and localization in the filopodia of the advancing plasma membrane

A cDNA library constructed from mRNA of rat brain was used to clone the cDNA that encodes the 30-kDa heparin-binding protein (amphoterin) that is developmentally regulated in brain and enhances neurite outgrowth in cerebral neurons. cDNA and peptide sequencing identified a dipolar sequence that has been previously found in studies of high mobility group 1 protein: the 184-amino acid cationic region is followed by a cluster of 30 anionic residues. The mRNA encoding amphoterin is also developmentally regulated; it is strongly reduced in quantity after the rapid perinatal growth phase of the rat brain. Anti-synthetic peptide antibodies raised according to the sequence of amphoterin were shown to bind specifically to the protein isolated from brain, and were used to detect amphoterin in subcellular fractions and in immunostaining of cells. Amphoterin was found in the cytoplasm of the cell soma, in the cell processes, and the substrate-attached material. In cells that are at an active stage of spreading and extending their cytoplasmic processes amphoterin was especially associated with plasma membrane filopodia. The distinct localization to the filopodia of the advancing plasma membrane suggests that endogenous amphoterin has a role in the extension of neurite-type cytoplasmic processes in developing cells. This inference is further supported by the finding that both anti-amphoterin and the anti-synthetic peptide antibodies in the culture media strongly inhibit the outgrowth of cytoplasmic processes.     

Diverse paths to hybrid incompatibility in Arabidopsis

One of the most essential questions of biology is to understand how different species have evolved. Hybrid incompatibility, a phenomenon in which hybrids show reduced fitness in comparison with their parents, can result in reproductive isolation and speciation. Therefore, studying hybrid incompatibility provides an entry point in understanding speciation. Hybrid incompatibilities are known throughout taxa, and the underlying mechanisms have mystified scientists since the theory of evolution by means of natural selection was introduced. In plants, it is only in recent years that the high‐throughput genetic and molecular tools have become available for the Arabidopsis genus, thus helping to shed light on the different genes and molecular and evolutionary mechanisms that underlie hybrid incompatibilities. In this review, we highlight the current knowledge of diverse mechanisms that are known to contribute to hybrid incompatibility.     

Reproductive meristem fates in Gerbera

Flowering plants go through several phases between regular stem growth and the actual production of flower parts. The stepwise conversion of vegetative into inflorescence and floral meristems is usually unidirectional, but under certain environmental or genetic conditions, meristems can revert to an earlier developmental identity. Vegetative meristems are typically indeterminate, producing organs continuously, whereas flower meristems are determinate, shutting down their growth after reproductive organs are initiated. Inflorescence meristems can show either pattern. Flower and inflorescence development have been investigated in Gerbera hybrida, an ornamental plant in the sunflower family, Asteraceae. Unlike the common model species used to study flower development, Gerbera inflorescences bear a fixed number of flowers, and the architecture of the flowers differ in that Gerbera ovaries are inferior (borne below the perianth). This architectural difference has been exploited to show that floral meristem determinacy and identity are spatially and genetically distinct in Gerbera, and we have shown that a single SEPALLATA-like MADS domain factor controls both flower and inflorescence meristem fate in the plant. Although these phenomena have not been directly observed in Arabidopsis, the integrative role of the SEPALLATA function in reproductive meristem development may be general for all flowering plants.     

Propensity for paternal inheritance of de novo mutations in Alexander disease

De novo dominant mutations in the GFAP gene have recently been associated with nearly all cases of Alexander disease, a rare but devastating neurological disorder. These heterozygous mutations must occur very early in development and be present in nearly all cells in order to be detected by the sequencing methods used. To investigate whether the mutations may have arisen in the parental germ lines, we determined the parental chromosome bearing the mutations for 28 independent Alexander disease cases. These cases included 17 different missense mutations and one insertion mutation. To enable assignment of the chromosomal origin of the mutations, six new single nucleotide polymorphisms in the GFAP gene were identified, bringing the known total to 26. In 24 of the 28 cases analyzed, the paternal chromosome carried the GFAP mutation (P<0.001), suggesting that they predominantly arose in the parental germ line, with most occurring during spermatogenesis. No effect of paternal age was observed. There has been considerable debate about the magnitude of the male to female germ line mutation rate; our ratio of 6:1 is consistent with indirect estimates based on the rate of evolution of the sex chromosome relative to the autosomic chromosomes.     

Interactive effect of elevated temperature and O<Subscript>3</Subscript> on antioxidant capacity and gas exchange in <Emphasis Type="Italic">Betula pendula</Emphasis> saplings

We studied the effects of slightly elevated temperature (T), O₃ concentration (O₃) and their combination (T + O₃) on the antioxidant defense, gas exchange and total leaf area of Betula pendula saplings in field conditions. During the second year of the experiment, T enhanced the total leaf area, net photosynthesis (P _n) and maximum capacity of carboxylation, redox state of ascorbate and total antioxidant capacity in the apoplast. O₃ did not affect the total leaf area, but P _n was slightly and g _s significantly reduced. The saplings responded to elevated O₃ level by closing the stomata and by developing leaves with a lower leaf area per mass, rather than by accumulating ascorbate in the apoplast. The effects of T and O₃ on total leaf area and P _n were counteractive. Elevated O₃ reduced the saplings’ ability to utilize the warmer growth environment by increasing the stomatal limitation for photosynthesis and by reducing the redox state of ascorbate in the apoplast in the combination treatment as compared to T alone.     

Bifidobacterium and Lactobacillus DNA in the human placenta

Aims:  Bifidobacteria and lactobacilli are part of the human normal intestinal microbiota and may possibly be transferred to the placenta. It was hypothesized that intestinal bacteria or their components are present in the placenta and that the foetus may be exposed to them. We investigated the presence of bifidobacteria and lactobacilli and their DNA in the human placenta.
Methods and Results:  We studied 34 human placentae (25 vaginal and nine caesarean deliveries) for the presence Bifidobacterium spp. and Lactobacillus rhamnosus. Cultivation was used for the detection of viable cells and genus and species-specific PCR for the detection of DNA. No bifidobacteria or lactobacilli were found by cultivation. Bifidobacterial DNA was detected in 33 and L. rhamnosus DNA in 31 placenta samples.
Conclusions:  DNA from intestinal bacteria was found in most placenta samples. The results suggest that horizontal transfer of bacterial DNA from mother to foetus may occur via placenta.
Significance and Impact of the Study:  Bacterial DNA contains unmethylated CpG oligodeoxynucleotide motifs which induce immune effects. Specific CpG motifs activate Toll-like receptor 9 and subsequently trigger Th-1-type immune responses. Although the newborn infant is considered immunologically immature, exposure by bacterial DNA may programme the infant's immune development during foetal life earlier than previously considered.